1. Field of the Invention
The invention herein relates to ice manufacturing and conveyance systems. More particularly it pertains to cleaning and sanitation of ice and ice conveyance systems.
2. Description of the Prior Art
Ice conveyance systems are used to move quantities of ice cubes from where they are formed or stored to where they are needed for dispensing for use. A typical application would be in a restaurant (such as a fast food outlet) to move ice cubes from an ice forming machine to an ice and beverage dispenser (IBD) from which the ice cubes can be individually dispensed such as into the beverage containers of the restaurant""s patrons.
Water which is used to make ice in such ice conveyance systems will contain varying quantities of foreign materials, notably particulate materials and bacteria. Where water supplies are carefully monitored and treated, as in most municipalities in the major industrial countries, the concentrations of such materials in water supplies are normally maintained at low levels which scientific studies have found to present no significant risks to public health. However, even where the water supplies thus overall contain low, safe levels of particulate materials and bacteria, systems which use such water can contain areas where such particulates and especially bacteria can accumulate to excessive concentrations. As water or ice which is initially free of unsafe concentrations of particulates or bacteria passes into or through such high concentration areas, the water or ice can pick up additional particulates and/or bacteria, sufficient to raise the concentrations of such foreign materials in the water or ice to undesirable levels.
Further, while safe water and ice may be available in larger, more scientifically sophisticated municipalities, in rural areas and in less developed countries water and ice contamination in the form of elevated, undesirable concentrations of particulates, and most especially bacteria, is frequently present. Travellers to many areas are commonly warned to boil or disinfect local water supplies and not to use ice in beverages to avoid becoming ill from such contamination.
Ice conveyance systems can be relatively simple with only one or a few conduits or they can be quite complex with many conduits. In either case the systems almost invariably contain some areas where undesirable levels of contamination, especially bacteria, can accumulate. It is therefore necessary to keep the conduits clean and particularly to keep them free from bacterial contamination. However, cleaning and sanitizing conduits is difficult. It is usually impractical to disassemble the conduits to gain access to their interiors for cleaning, particularly since most conduits are placed in relatively inaccessible locations such as in a suspended ceiling. As a result it has become common in practice to try to clean and sanitize conduits by passing antibacterial and cleansing liquids through the conduits and collecting the spent liquids (with accumulated materials) at one or more outlet points along the conduit runs. This has only been partially successful for several reasons. First, the liquids tend to accumulate at low spots in the conduits, so that stagnant pools of liquid and bacteria remain in the systems. Second, these cleansing liquids are themselves foreign materials in the systems and can leave residues that will contaminate the ice that subsequently passes through the conduits. Third, the cleansing components often are relatively ineffective in removing all bacterial contamination, since bacteria can be lodged in joints and other locations in the conduits which are not accessible to the liquids.
Since most ice conveyance systems are used in food service and beverage service settings, such as restaurants, hotels and motels, hospitals and similar locations, there is of course a great deal of emphasis on keeping the conveyance systems as clean and sanitary as possible. It would therefore be advantageous to have a cleaning and sanitizing system that would be effective throughout an ice conveyance system, would not involve the use of foreign liquids and could be run on essentially a continuous basis.
Ozone (O3) is known to be an oxidizing agent, antiseptic and disinfectant, to be an effective biocidal agent against various pathogens including bacteria and vegetative cells, and to be used for water purification; Brock et al., BIOLOGY OF MICROORGANISMS, pp. 349-351, 544-550 (5th ed., Prentice-Hall: 1988); Sax et al., HAWLEY""S CONDENSED CHEMICAL DICTIONARY, pp. 866-867 (11th ed., Van Nostrand Reinhold: 1987). It has also been reported to have been used to sterilize ice used in cold storage holds of fishing vessels to provide a sterile bed within the holds for the fish catch accumulated while the vessel is at sea.
It would therefore be advantageous if a system were available which could easily and thoroughly clean and sanitize ice during manufacture and conveyance systems for the manufactured ice. It would also be advantageous for that system to be capable of producing clean, uncontaminated ice.
In the present invention, ozone is injected into the water supply to any ice maker. The presence of the ozone kills bacteria and other microbial contaminants in the water, and ozone content is maintained in the water so that when the water is frozen into ice in an ice maker in the system of the invention, a significant ozone content is present in the ice. This ice may be recovered for human consumption, a definite advantage in those locales where use of ice in beverages and for other food contact must normally be avoided because of microbial contamination.
As a further aspect of the invention, the ice manufactured in the ice maker is conveyed (along with some accompanying water) under gas (usually air) pressure or vacuum through a conveyance system to one or more locations remote from the ice maker, where the ice is to be used. Such conveyance systems are intended for restaurants (especially fast food outlets), hotels, motels, hospitals, and numerous other facilities where ice is required for use by patrons, staff, patients, etc. at locations such as ice and beverage dispensers, ice chests and storage containers, chilled food counters and ice displays, ice bag filling machines, and the like. An unique and particularly preferred system, which conveys ice to remote locations under vacuum, is described and claimed in pending U.S. patent application Ser. No. 09/364,794, filed Jul. 30, 1999, entitled xe2x80x9cVacuum Pneumatic System for Conveyance of Ice.xe2x80x9d
As the ice and water move through the conduits and components of the conveyance system, ozone is evolved from the water and from the ice as the ice melts, sublimes or is abraded. Similarly, ozone is evolved in the same manner when the ice and water sit in storage containers, either those used for initial distribution of the ice from the ice maker to the conveyance system or those at the remote locations where the ice is to be used. In both cases, the gaseous ozone evolved acts as a powerful oxidizing agent and disinfectant, and kills substantially all microbial materials which are within the system. Since the ozone is a gas, it can penetrate into all areas of the system, including those which liquid cleaners and disinfectants cannot reach, and it can become incorporated into the thin layers of moisture which are present on the interior walls of conduits, diverters, valves, etc., throughout the system, such that it provides superior and thorough cleaning and sanitizing of the system. It is also effective in cleaning and sanitizing the ancillary parts of the systemxe2x80x94the ice maker, the receiver bins in remote ice dispensers, storage bins from which ice is drawn at times of high demand, and so forth. Once the microbial contaminants initially present are eliminated, operation of the invention serves to maintain that state of cleanliness, since passage of more ice or water though the system causes the evolution of additional ozone, which in turn kills any microbial contamination which may subsequently get into the system.
In addition, the system operator can also conduct periodic washes of parts or all of the system by running ozonated water from the water supply tank through the system without having to operate the system to make ice. Such water washes are conveniently done at the time of a startup and at intervals (perhaps monthly or quarterly) over the course of regular ice service. Such washes perform a comprehensive cleaning which enhances the ability of the regular operation of the system to maintain a high degree of cleanliness and sanitation in the system and all ancillary equipment.
Numerous microbial contaminants can be controlled or eliminated by this invention, including but not limited to species of Salmonella, Escherichia (including E. coli), Campylobacter, Leptospira, Shigella, Enterobacter, Cryptosporidia, Paramecia, and Giardia.
The invention is applicable to conveyance systems of any degree of complexity, with a few or many branches and a few or many remote location ice receivers. It can be used with relatively clean water supplies, such as those from many municipalities, or with water supplies containing significant amounts of particulate matter, such as may be found in rural or underdeveloped areas.
Therefore, in a principal embodiment, the invention involves a method for producing ice which is free of contamination from microbial organisms which comprises providing an ice maker and water for the ice maker; incorporating ozone into the water prior to passage of the water to the ice maker; maintaining the water under conditions to restrict evolution of the ozone from the water prior to freezing of the water in the ice maker, providing ozone-containing water to the ice maker and therein causing the ozone-containing water to freeze to form the ice, such that the ice contains the ozone and is substantially free of any concentration of microbial organisms.
In another principal embodiment, the invention involves a method for controlling the presence of microbial organisms in the interior of an ice conveyance system which comprises: in the ice conveyance system providing an ice maker, an ice receiver, an enclosed conduit through which ice can be conveyed between the ice maker and the ice receiver, and gas flow means for conveying the ice through the conduit; providing water for the ice maker; injecting ozone into the water; thereafter passing the ozone-containing water to the ice maker and causing the ozone-containing water to freeze within the ice maker to form the ice, such that the ice contains the ozone; and thereafter passing the ice containing the ozone from the ice maker through the conduit to the ice receiver; whereby as the ice resides in or passes through the ice maker, conduit and ice receiver, at least some of the ozone is evolved as gas from the ice cubes and disperses throughout interiors of the ice maker, conduit and ice receiver, therein contacting and killing microbial organisms which are present therein.
In yet another principal embodiment the invention is of apparatus for producing ice which is free of contamination from microbial organisms which comprises an ice maker; a supply of water for the ice maker; incorporating means for incorporating ozone into the water prior to supply thereof to the ice maker; and control means for maintaining the water under conditions to restrict evolution of the ozone from the water prior to freezing of the water in the ice maker, such that when the ozone-containing water is frozen in the ice maker to form the ice, the ice contains the ozone and is substantially free of any concentration of microbial organisms.
In yet another principal embodiment the invention is of apparatus for controlling the presence of microbial organisms in the interior of an ice conveyance system comprising the ice conveyance system which itself comprises an ice maker, an ice receiver, an enclosed conduit through which ice can be conveyed between -the ice maker and the ice receiver, and gas flow means for conveying the ice through the conduit; a supply of water for the ice maker; incorporation means for incorporating ozone into the water; the ice maker freezing the ozone-containing water to form the ice, such that the ice contains the ozone; and motivating means for passing harvested ice containing the ozone from the ice maker through the conduit to the ice receiver; such that as the ice resides in or passes through the ice maker, conduit and ice receiver, at least some of the ozone is evolved as gas from the ice cubes and disperses throughout interiors of the ice maker, conduit and ice receiver, therein contacting and killing microbial organisms which are present therein.
Other embodiments and variations will be evident from the descriptions below.